Resistance-heated boat and manufacturing method thereof

Abstract

Disclosed herein are a resistance-heated boat and a manufacturing method thereof for use in vacuum vapor deposition of a metal evaporant onto a substrate in a resistance heating manner. The boat comprises a graphite block to be formed into a boat, and a protective barrier formed at the graphite surface for preventing the graphite layer from reacting with the metal evaporant. The protective barrier has an aluminum-rich layer, and a nitrogen containing compound layer. According to the present invention, it is possible to achieve stable and continuous evaporation of metals including aluminum.

Description

TECHNICAL FIELD [0001] The present invention relates to a resistance-heated boat employed for the deposition of thin films using vacuum vapor deposition, and a manufacturing method thereof. More particularly, the present invention relates to a resistance-heated boat, and a manufacturing method thereof, the resistance-heated boat being manufactured by forming graphite into a boat, and coating it with specific compounds, thereby enabling stable and continuous evaporation of metals, such as aluminum. BACKGROUND ART [0002] As well known to those skilled in the art, vacuum vapor deposition is a general technique for coating materials, such as aluminum, silver, gold, copper, and tin on metal, glass, or plastic substrates, and is one of the physical vapor deposition (PVD) techniques using vacuum. In recent years, the PVD techniques have been increasingly applied since they less adversely affect the environment compared to existing wet plating techniques. The PVD techniques include vacuum v...

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Benefits of technology

[0013] Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a resistance-heated boat, which is made of inexpensive graphite, and enables stable and continuous evaporation of metals, such as aluminum, having a poor wetting capability and a high reactivity with the graphite thereof, and a manufacturing method thereof.

[0017] In accordance with another aspect of the present invention, there is provided a method of manufacturing a resistance-heated boat for use in vacuum vapor deposition, comprising the steps of; a) forming a graphite block into a boat having an evaporation cavity formed at a surface thereof for positioning the metal evaporant, such as aluminum; b) coating the surface of the graphite with a nitrogen containing compound; c) producing a protective barrier at the surface of the graphite surface by positioning the aluminum inside the evaporation cavity formed at the center of the graphite boat, and causing a reaction between the aluminum and the nitrogen containing compound through a heat treatment process, the protective barrier serving to prevent the graphite surface from reacting with the molten evaporant.

Problems solved by technology

The induction heating source is mainly used in large-scale coating apparatus since it has a tendency of employing complicated peripheral devices due to the use of high frequencies.

The electron beam heating source, however, has a disadvantage of being expensive.

The resistance heating source is used in various fields because of their simple installation and inexpensive price features, but it also has a disadvantage in that it can evaporate only a limited range of materials.

This makes it difficult for the aluminum to be evaporated by using the conventional boat, since aluminum causes damage to the boat as it produces compounds by reacting with refractory metals constituting the boats.

Although this method achieves high evaporation rate, it has a disadvantage of an extremely short life time due to the fact that the aluminum reacts with the surface of the tungsten filaments and in turn the filament is damaged, as it spreads throughout the surface of the tungsten filament.

The BN boat, however, has a problem in that they are very expensive since they are manufactured by sintering relatively expensive raw materials under the high temperature and pressure.

Such a BN boat has a further problem in that it is essentially impossible to recycle them, and thus in order to solve this problem, U.S. Pat. No. 4,847,031 discloses a recycling means for the BN boats.

The disclosed recycling means of the BN boats, however, are not particularly advantageous from an economic standpoint since it must pass through a process similar to the initial manufacturing process thereof.

Furthermore, the conventional BN boat has yet another problem of a splash phenomenon wherein molten aluminum lumps are often ejected from the boat, and adhere to the substrate.

The resistance-heated boat made of the graphite, however, exhibit several problems in relation to the evaporation of reactive materials such as aluminum since the aluminum produces intermetallic compounds such as Al4C3 by reacting with the graphite.

Therefore, the graphite has been restrictively used as a crucible for use in induction heating evaporation source, electron beam source liner, and the like.

In cases where the graphite is used in the boats for evaporating copper or silver, the evaporants are scattered due to their low wetting properties, thereby causing a deterioration in evaporation efficiency (rate) and consequently a difficulty in use thereof.

Further, in cases of the boat for evaporating aluminum or iron having a high reactivity with the graphite, the evaporant attacks the boat and eventually the boat is broken at high temperature.

In the above-mentioned patent, although it has no problem in the case of intermittent evaporation for experimental applications, when it is necessary to continuously evaporate materials such as aluminum, there is a problem in that the aluminum as an evaporant flows out of the evaporating surface of the boat and reacts with the graphite surface of the boat in a holder region provided in a vacuum vapor deposition apparatus, thereby causing damage to the boat and causing the evaporant to be deposited on the holder region, and that a great amount of the aluminum is not evaporated, resulting in a serious loss of aluminum.

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